While the prevalence of smoking has decreased among youth, the prevalence of e-cigarette (e-cig) use has recently increased dramatically, greatly exceeding that of cigarette use. The increased prevalence of e- cig use among youth, the health effects of e-cigs, and the increased probability that adolescents will become addicted to nicotine through the use of e-cigs provide support for the crucial need for the incorporation of e-cig use into tobacco prevention programs targeting youth. Within the proposed Phase II project, we plan to integrate content targeting risk factors predictive of e-cig use into an existing effective school-based tobacco prevention program, Click City: Tobacco. Click City: Tobacco is designed for implementation in the 5th grade, with a booster in 6th grade, prior to the onset of tobacco use for most youth. Features of the program are that it is computer-based, assuring fidelity of implementation of the complete program, requires little teacher training time, allows students to work independently providing teachers with time to work individually with other students, and encourages student engagement through including interactive activities and affect-producing games. Within Phase I, we showed that we were able to 1) create two activities that changed specific risk factors predictive of e-cig use; and 2) modify two activities that previously targeted only cigarette use, to not only change risk factors predictive of e-cig use, but also to change risk factors predictive of smoking. Within Phase II, our goals are: (1) Develop additional content that specifically targets risk factors/mechanisms predictive of e-cig use to integrate into existing activities (not revised in Phase I) that previously targeted only conventional tobacco use. We will also modify most of the activities within the program to include e-cig use in the narration regarding tobacco use and change graphics as needed; (2) Update the entire program to HTML5/CSS/Java/ to increase marketability by expanding the range of devices on which the program can be delivered (e.g., tablets to desktops), simplifying the student user interface, and providing more robust teacher/administrator functionality; and (3) Conduct a randomized trial within 44 schools to assess: a) the effectiveness of the revised program on changing youth's intentions and willingness to use e-cigs and to smoke; and b) the logistics of implementing the program in the school setting. If the modified program is effective and is practical for use in the schools, wide-spread implementation as a result of effective marketing could have a large impact on public health, decreasing the use of nicotine products and subsequent disease.